Risk Factor Control Linked to Better Outcomes After Peripheral Intervention

A substantial proportion of patients with stable claudication continue to smoke and do not receive aspirin or statin therapy before undergoing endovascular treatment, according to registry findings published online December 11, 2012, ahead of print in Circulation: Cardiovascular Interventions. Patients on either medication at the time of admission, however, reduce their risk of peripheral vascular events by a third up to 6 months later.

P. Michael Grossman, MD, of the University of Michigan (Ann Arbor, MI), and colleagues examined the Blue Cross Blue Shield Michigan Cardiovascular Consortium Peripheral Vascular Intervention (BMC2 PVI) database to identify 1,357 patients with stable claudication who underwent peripheral vascular interventions from January 2007 to December 2009. Patients with contraindications to aspirin or statins were excluded from the analysis.

Improvement Seen During Hospitalization

Though risk control was not achieved in all patients, the proportion who were on both aspirin and statin therapy and did not smoke (or, among smokers, had completed tobacco cessation counseling before discharge) rose after percutaneous intervention (P < 0.01; table 1).

Table 1. Risk Factor Control Before and After Intervention

At 6 months, the rate of MACE (death, MI, or stroke/transient ischemic attack) did not differ between patients who were and were not taking aspirin/statin therapy before invasive treatment. Peripheral vascular events (composite of repeat peripheral intervention, limb salvage surgery, or amputation), however, were reduced in patients on the 2 drugs at baseline (table 2).

Table 2. Unadjusted Event Rates at 6 Months

After multivariable adjustment for age, race, sex, current smoking, diabetes status, prior cardiovascular events, previous peripheral interventions, and renal failure requiring dialysis, patients on 1 drug at baseline (either aspirin or statin) saw a reduced likelihood of adverse peripheral vascular events (OR 0.67; 95% CI 0.53-0.84). The risk was even lower for patients taking both drugs (OR 0.45; 95% CI 0.29-0.71).

The model did not correct for socioeconomic, geographic, or insurance-related factors, nor did the researchers have access to data on participation in supervised exercise programs or the adequacy of blood pressure or lipid control.

Results Stem from Concerted Effort

In a telephone interview, Dr. Grossman told TCTMD that medical therapy, particularly statin treatment, has been shown to improve outcomes after intervention in other vascular areas. As such, the current findings are not surprising. Further support comes from the fact that such a strong effect was seen in a relatively short follow-up duration, he said, noting that “there is probably something here.”

As to the lack of effect on MACE in the current study, Dr. Grossman explained, the “truth is that the majority of patients in the registry were on evidence-based medical therapy, at least on aspirin or statins, and we only followed them for 6 months. So we wouldn’t [expect to] see, say, a difference in mortality, or even MI, in patients who originally didn’t have active coronary artery disease at the time they had their peripheral intervention.

“Having said that, clearly there are areas for improvement,” he continued. “Maybe [these results] will spur all of us to make more efforts to make sure all our patients, when appropriate, are on these medications.”

Dr. Grossman reported that, as part of the BMC2 PVI initiative, there are now more than 40 Michigan hospitals participating in data collection and quality improvement. The multidisciplinary effort “is a unique opportunity for all of us taking care of these patients to work together. We’re seeing some [gains already, such as increased prescriptions for medical therapy at discharge]. We’re very hopeful that this is going to translate to improved outcomes.”

In this population with stable, lifestyle-limiting claudication, “it certainly is possible that if patients had been on more aggressive medical therapy . . . that some of them may have avoided the need for revascularization, but we really can’t say that for sure,” Dr. Grossman concluded. 

Study Details

Patients on aspirin/statin therapy at baseline tended to have more comorbidities and to have previously undergone coronary or peripheral revascularization. They also were more likely to be on beta-blockers and ACE inhibitors or ARBs.

 

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Source:
Ardati AK, Kaufman SR, Aronow HD, et al. The quality and impact of risk factor control in patients with stable claudication presenting for peripheral vascular interventions. Circ Cardiovasc Intv. 2012;Epub ahead of print.

 

 

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